This invention relates to the fabrication of semiconductor substrate material and more particularly to the preparation of single crystal gallium arsenide ribbon directly from the component sources.
Gallium arsenide substrates for various applications including solar cells are normally obtained by cutting the single crystal boule into wafers which are polished. The high cost of synthesizing GaAs from Ga and As, in terms of the furnace energy and containers, growing the boule, and producing the wafers by x-ray orientation, slicing and polishing, and the material lost along the processing, combine to make the GaAs devices economically impractical. Also, it is difficult to grow single crystals of sufficiently large size or with reproducible uniformity. A substrate of large area is in general of poor crystal quality. It is, therefore, desirable to devise a process for producing GaAs substrates in thin single crystal form, such as ribbons, directly from the component sources, and that these substrates be minimally defective so that breakage does not easily occur.